1. Field of the Invention
This invention relates in general to certain new and useful improvements in barrier devices which serve as a barrier to foreign substance migration throughout an opening in living animal tissue, and, more particularly, to barrier devices of the type stated which are formed of a flexible, resilient element capable of being deformable to conform to the surface of an animal and fully cover an opening in animal tissue and to also provide visual indication of the amount of tightness with which a rigid, or somewhat rigid, member is held in animal tissue.
2. Brief Description of the Prior Art
There have been several in-vivo temperature indicating devices which provide visual indication of temperature changes in generally domestic and semi-domestic animals, as for example, cattle. This information is valuable since the temperature changes may be indicative of a disease producing pathogen present in the animal. One such device, for example, is described in U.S. Pat. No. 3,889,658 to Newhall. Another device providing indication of temperature change is described in U.S. Pat. No. 4,083,364 to Kelly et al.
It is, of course, highly desirable to determine the presence of a pathogen causing disease or illness at an early stage in order to treat the animal before the illness or disease has progressed to a stage resulting in irreparable harm or terminal illness. Moreover, these temperature sensing devices have obviated the problem of periodic temperature measurements through anal thermometers and the like.
Temperature sensing devices of the types mentioned above usually include a stem insertable through an opening and into a cavity in the body of the animal. Particularly, it has been recognized that there is cavity in a region behind an animal's ears adjacent to its skull and formed by subcutaneous facia and fat in which the stem may be inserted. At its outer end, the stem is provided with some form of temperature indicating device providing visual warning of temperature change, and which is responsive to a member in the stem for indicating temperature change in the animal body. These devices are designed for relatively permanent implant in the animal.
One of the primary problems with the use of these devices is that the opening never fully heals with the relatively permanent temperature indicating mechanism disposed in the animal's body through the opening. In addition, the opening serves as a pathway for foreign substances, typically the passage of bacteria which may cause an infection in the animal and which can result in illness of the animal. In addition, percutaneous installation of an apparatus formed of a material which is foreign to the living body tissue has resulted in the rejection of the apparatus as a result of migration through the opening of bacteria, germs, foreign particles, moisture and other foreign substances present on the surface of the animal body.
There have been attempts to utilize powder or salves or liquid medications injected into or located around the surface of an incision which receives the percutaneous member in order to promote healing. However, the wetting from the wound and the liquification of the medication on the exterior tissue causes migration of the medication into the wound which also carries undesirable surface contaminants into the animal body. In this respect, the wound serves as a reversely acting "wet wick" which not only would carry in the medication, but also the various undesirable surface contaminants and which subsequently may produce infections or other conditions detrimental to the health of the animal. In this respect, the wet wound acts somewhat in the manner of a wick to foreign substances since it has a tendency to pull foreign substances. Further, since the wet wound tends to pull such substances inwardly, it acts as a reversely acting wet wick.
Temperature sensing devices and other devices for relatively permanent implant in an animal may include expandable arms which are expandable upon a manual screwing action on a portion of the stem external to the animal. However, it is difficult to determine when the arms have fully expanded so that overscrewing and necrosis does not result.
The present invention overcomes these and other problems in providing a foreign substance barrier device which effectively restrains the migration of foreign substances of any origin into the animal's body through an incision formed therein and which thereby reduces the rejection of a percutaneous member inserted through the incision and into the animal's body. The device of the present invention also serves as an effective indicator or tightness so that overscrewing or other tightening action does not occur which would otherwise result in necrosis.